The practical use of displays and lighting devices utilizing an organic electroluminescence device (organic EL device) has recently studied more actively. In particular, reducing cost and growing in size of screen are given as a big issue. Therefore, there is an increasing expectation for transition from traditional vacuum deposition type organic EL devices to (solution) coating type organic EL devices. When organic EL devices are of the coating type, the followings are expected: high material use efficiency, easy film-formation of a large screen and inexpensive apparatus cost due to no vacuum system.
Here, there are low-molecular and high-molecular materials as an organic EL material for a coating type organic device. The high-molecular material is preferable from the view points of solubility, coating uniformity and stacked devices. In particular, development of high-molecular materials for a hole-transporting (injecting) layer which can be used in common for displays and lighting devices is desirable.
Patent Documents 1 to 3 disclose high-molecular materials for a hole-transporting (injecting) layer. However, these materials have various problems such as insufficient hole-transporting function (mobility) and insufficient solubility in coating solvents.